1. Chapter 15 Holt
Chemical Reactions

2. Using Vocabulary
1. Adding a(n) inhibitor will slow down a chemical reactions.
2. A chemical reaction that gives off light is called exothermic.

3. 3. A chemical reaction that forms one compound from two or more substances is called a synthesis reaction.

4. 4. The 2 in the formula Ag2S is a subscript.
5. The staring materials in a chemical reaction are reactants.

5. Understanding Concepts
6. Balancing a chemical equation so that the same number of atoms of each element is found in both the reactants and the products is an illustration of
C) the law of conservations of mass.

6. 7. What is the correct chemical formula for calcium chloride?
B) CaCl2
Ca has a valence of 2, so 2+ charge
Cl has a valence of 7, so -1 charge
So 2 Cl- with Ca++ makes CaCl2

7. 8. In which type of reaction do ions in two compounds switch places?
D) double-replacement
Ex: NaOH + HCl --> NaCl + H2O

8. 9. Which is an example of the use of activation energy?
C) holding a match to paper

9. 10. Enzymes in your body act as catalysts. The role of enzymes is to
A) Increase the rate of chemical reactions (make the reactions happen faster)

10. Short Answers 11. Classify each of the following reactions:
A) Fe + O2 --> Fe2O3 synthesis
Balanced this would be
4Fe + 3O2 --> 2Fe2O3
Iron + oxygen --> rust

11. B) Al + CuSO4 --> Al2(SO4)3 + Cu
single replacement
Balanced this is
2Al + 3CuSO4 --> Al2(SO4)3 + 3Cu
Aluminum + cupric sulfide --> aluminum sulfide plus copper

12. C) Ba(CN)2 + H2SO4 --> BaSO4 +HCN
Double replacement
Balanced this is
Ba(CN)2 + H2SO4 --> BaSO4 + 2HCN

13. 12. Name two ways that you could increase the rate of a chemical reaction.
1) raise the temperature
( this increases the concentration and/or the surface area)
2) add a catalyst

14. 13. The reactants are acetic acid (vinegar) and baking soda (sodium bicarbonate).
The products are carbon dioxide CO2 , water H2O, and sodium acetate.

15. 14. Concept map is on the white board.
Terms are:
Chemical reaction
Chemical equation
Chemical formulas
Reactants, products,
Coefficients, subscripts

16. Critical Thinking & Problem Solving
15. Your friend is very worried by rumors he has heard about a substance called dihydrogen monoxide. What could you say to your friend to calm his fears?
Dihydrogen H2
Monoxide O
So H2O - not to worry - its water !

17. 16.
As long as proper safety precautions have been taken, why can explosives be transported long distances without exploding?
Explosives need to absorb energy to being the reaction. Without this absorption, they can be transported safely.

18. Math in Science
17. Calculate the number of atoms of each element shown in each of the following:
A) CaSO4
Ca - Calcium - 1 atom
S - Sulfur - 1 atom
O - Oxygen - 4 atoms

19. B) 4NaOCl
Na - sodium - 4 atoms
O - oxygen - 4 atoms
Cl - chlorine - 4 atoms

20. C) Fe(NO3)2
Fe - iron - 1 atom
N - nitrogen - 2 atoms
O - oxygen - 6 atoms

21. D) 2Al2(CO3)3
Al - Aluminum - 4 atoms
C - carbon - 6 atoms
O - oxygen - 18 atoms

22. 18. Write balanced equations for the following:
A) Fe + O2 --> Fe2O3

23. 18. Write balanced equations for the following:
A) Fe + O2 --> Fe2O3
Answer:
4Fe + 3O2 --> 2 Fe2O3

24. B) Al + CuSO4 --> Al2(SO4)3 + Cu
Answer

25. B) Al + CuSO4 --> Al2(SO4)3 + Cu
Answer
2Al + 3CuSO4 --> Al2(SO4) Cu

26. C)
Ba(CN)2 + H2SO4 --> BaSO4 + HCN

27. C)
Ba(CN)2 + H2SO4 --> BaSO4 + HCN
Answer
Ba(CN)2 + H2SO4 --> BaSO4 + 2HCN

28. 19) Balanced chemical equations:
A) bromine reacts with sodium iodide to form iodine and sodium bromide
Br2 + 2NaI --> I NaBr

29. B) Phosphorus reacts with oxygen gas to form diphosphorus pentoxide
4P + 5O2 --> 2P2O5

30. C) Lithium oxide decomposes to form lithium and oxygen
2Li2O --> 4Li + O2

31. Interpreting Graphics
20. In the photo on page 393, what evidence supports that this is a chemical reaction?
Answer
- Bubbles of gas are produced
- Light is given off

32. 21. Using the energy diagram on page 393, answer q’s a,b,c
A) “C” represents the energy of the products (far right section of graph)
B) “B” represents the activation energy of the reaction (increases then peaks)
C) Energy is “given off” by this reaction.
That’s the decline of energy below starting energy mark - “D” on the chart)